Structural Evidence of Mechanical Shuttling in Condensed Monolayers of Bistable Rotaxane Molecules

✍ Scribed by Kasper Nørgaard; Bo W. Laursen; Sune Nygaard; Kristian Kjaer; Hsian-Rong Tseng; Amar H. Flood; J. Fraser Stoddart; Thomas Bjørnholm

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 236 KB
• Volume: 44
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.200501538

✦ Synopsis

Bistable, redox-controllable [2]rotaxanes constitute a class of artificial molecular machines [1,2] in which a mobile ring is confined to move between two different recognition sites (stations) along a dumbbell-shaped component. Linear motor molecules and nanoelectromechanical actuators [3] can be constructed from such redox-controllable [2]rotaxanes. These latter compounds have also been utilized [4, 5] as electromechanical switches in molecular memory devices. In this context, the possibility of relative mechanical motion occurring within such bistable [2]rotaxanes in condensed phases has been questioned [6] and disputed. [7] Such motion has been demonstrated unequivocally in solution, [8] in polymer matrices, [9] and in self-assembled monolayers on gold electrodes [10] to result in the movement of the ring from one primary station to a secondary one and then back again in a stepwise manner. One glaring deficiency, however, has been the lack of structural characterization methods for these switching processes in nanoscale systems that can be applied directly to highly condensed phases on surfaces and at interfaces.